Here is a video of seven-year-old Yo-Yo Ma playing with his sister, Yeou-Cheng Ma (*), at the Benefit for the National Cultural Center (**), on Nov 29, 1962, in front of President John Kennedy, First Lady Jacqueline Kennedy, and former President Eisenhower - all of whom you can get a glimpse of after the performance is over. The master of ceremonies is the great Leonard Bernstein.
(*) "This Is New York: The Untold Story of Dr. Yeou-Cheng Ma, Violin Prodigy and Medical Doctor" by Amelia Pang on theepochtimes.com
(**) Ominously, just two years later, the National Cultural Center was renamed the John F. Kennedy Center in honor of the fallen President.